Un sure of what to do, and needs some advice.

Ok, well I think I'm in love with this girl (lets call her Sarah) , but I'm not sure.. kinda confusing. And then there's her friend (call her Jill). Now me and sarah are pretty good friends, we've been ut on a few dates everythign always goes well. But she doesnt like me in that way (at least no that think, i think she likes me a bit, i know she used to )... but shes all i ever think about, and im scared to let her know how i really feel about her, theres also the thing of her past which i think is holding her back ( to sum it up shes scared she'll be cheated on).
And then theres Jill no I like jill to, not nearly as much as i like sarah. But if things between me and sarah were to every work out id have to quite some of my not so good habits.. then with jill i wouldnt, infact she supports them. Right now im not sure what to do, hold out for sarah.. or go for jill.